Papillomaviruses are understood to be very important causal agents in human disease. As part of their normal life cycle, these viruses infect and transform cells in the epithelium causing benign tumors that with a low but significant frequency can become malignant. A deeper understanding of the life cycle in general, and DNA replication in particular, is of critical importance for the understanding of the disease, its transmission and ultimately for the development of effective therapeutic measures. Although recently developed vaccines promise to reduce the prevalence of this disease, for the foreseeable future papillomavirus infections will still present a formidable problem due to the large number of already infected individuals. Thus treatment options such as small molecule inhibitors of the viral life cycle would be desirable. Compared to other disease causing viruses very limited effort has been invested in identifying targets for small molecule intervention in papillomaviruses. Work by us and others have now reached the point where we can pinpoint particular aspects of the viral replication machinery that represent plausible targets for small molecule interference with viral replication. In this proposal we will focus on the function of viral initiator protein E, which is a key factor in viral DNA replication. In Specific Aim 1, we propose to determine how phosphorylation by the protein kinase CK2 regulates the function of the E1 protein. In Specific Aim 2, we will analyze the biochemical function of novel activities present in the N-and C-terminal domains, which are critically important for E1 oligomerization. In Specific Aim 3 we will determine the biological function of the novel E1 interactions that we have uncovered.